Interrelations of pubertal development and adolescent adjustment and behavior are investigated cross-sectionally and longitudinally. Participants are 9- to 14-year-old boys and girls and their parents. the adolescents and their parents are seen three times, six months apart. Measures of pubertal development include serum hormone levels (gonadotropins, sex steroids, and adrenal androgens), pubertal stage (Tanner criteria), and height and weight. Psychological assessments of the adolescent include adolescent- and parent-report of behavior problems and competencies and behavioral observations of parents and their adolescent in family interactions. Comparisons of rating of pubertal stage made by medical personnel, the adolescents, and their parents indicate that, with appropriate instruction, adolescents and parents can provide valid assessments of the adolescent's pubertal stage. Analyses involving pre- and postmenarchial girls indicate that mean levels of gonadotropins, sex steroids, and adrenal androgens are higher in postmenarchial than premenarchial girls, but that there is considerable overlap in the distributions. Preliminary analyses suggest that there are similar hormone-behavior relations in pre- and postmenarchial girls. An examination of relations between hormone levels and the adolescents' use of anger and power in family interactions indicates that estradiol and androstenedione levels are related to irritability and assertive forms of aggression shown by girls. For both sexes, there was evidence that controlling behaviors shown by parents and anger shown by adolescents are related in a pattern which results in an escalation of conflict.